NORWALK -- The Third Taxing District Electric Department has begun giving the city a phased-in bill reduction for operation of Norwalk's wastewater treatment plant.

On Monday evening, Department of Public Works staff informed members of the Water Pollution Control Authority that the taxing district had been overbilling the city on the electric bill for the plant.

"The Third Taxing District completed a cost-of-service study and divulged that they've been billing the treatment plant more than they should have been all these years," said Ralph Kolb, the city's wastewater system manager. "So they've agreed to make an adjustment of 5 percent this year, and I think ultimately, trying to reach about a 10-percent correction. So it would be phased."

On Oct. 1, the WPCA saw an almost 5-percent reduction in its electric bill. Overall, the 5-percent reduction will result in a $60,000 savings for the fiscal year Oct. 1, 2014, through Sept. 30, 2015. The yearly electric bill will drop from about $1.2 million to $1.14 million, according to Kolb.

"We have been trying to negotiate a fair electric rate for five years or more," said Lisa Burns, operations manager at the public works department. The taxing district "got a new general manager over the last couple years, and we requested, again, that they do a cost-of-services study."

James W. Smith, Third Taxing District general manager, was not at the WPCA meeting at the Public Works Center on Monday evening, but spoke afterward about the rate reduction.

"We had a rate study early in 2014 and that study basically showed that we were billing our customers correctly, but ended up having a situation where we overbilled customers at the water treatment plant for a period of time," Smith said. "The rate consultant recommended that we give them a phased-in-rate decrease over time."

That rate reduction will be 5 percent in year one, 4 percent in year two and 2.5 percent in year three, according to Smith.

"The rate consultant found that we were billing all our other customers correctly," Smith said.